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Fuel Cost Calculator

Enter a trip distance, your fuel efficiency in mpg or L/100km, and the price of fuel to get the total cost, the fuel you need, and the cost per mile or kilometre.

Fuel efficiency unit

Gallon

A UK gallon is about 20% larger than a US gallon, so it changes the math.

Trip

Round trip doubles the distance you enter.

Currency

Everything is calculated in your browser. Nothing is uploaded.

Total fuel cost
$35.00300 mi one way
Breakdown
10
Fuel needed (gallons)
$0.12
Cost per mi
$11.67
Cost per 100 mi
7.8
Efficiency (L/100km)

How to calculate fuel cost for a trip online

  1. Pick your units

    Choose miles per gallon or litres per 100 km, set the trip to one way or round trip, and pick your currency and gallon size if you use miles per gallon.

  2. Enter distance, economy, and price

    Type the trip distance, your vehicle's fuel efficiency, and the current price of fuel. The total updates as you type, with no button to press.

  3. Read the cost and breakdown

    See the total fuel cost, the volume of fuel needed, and the cost per mile or kilometre, then copy the summary for your notes.

Why use this tool

Miles per gallon or litres per 100 km

Switch fuel economy between mpg and L/100km with one tap. The distance and price fields change unit to match, and the result also shows the equivalent economy in the other system.

Cost per mile and per 100

Alongside the total it breaks out the cost per mile or kilometre and the cost per 100, so you can compare journeys of different lengths on the same footing.

Round trip in one tap

A round trip toggle doubles the distance for a there and back journey without making you re-enter the number or reach for a calculator.

US or UK gallons

In miles-per-gallon mode you can pick a US or UK gallon, since the two differ by about 20% and quietly change the fuel and cost figures.

Runs entirely in your browser

Everything is calculated on your device as you type. Nothing you enter is uploaded, stored, or logged.

About this tool

This fuel cost calculator turns a trip into a number: how much you will spend on fuel to cover a given distance. Enter the distance, how far the vehicle goes on a unit of fuel, and the current price, and it works out the total cost, the volume of fuel you need, and the cost per mile or kilometre. Every figure updates the moment the three inputs are valid, so you can nudge the price or the distance and watch the total move.

Fuel economy can be entered as miles per gallon or as litres per 100 km, and the distance and price fields follow the unit you pick. Because a UK gallon holds about 20% more than a US gallon, miles-per-gallon mode lets you choose which one your figure uses, so imported quotes and local pump prices both come out right. A round trip toggle doubles the distance for a there and back journey, and the equivalent economy in the other unit is shown next to the cost.

It is handy for budgeting a road trip, splitting fuel between passengers, or comparing two cars before a long drive. To switch a distance or a fuel figure between units on its own, the unit converter does the direct conversion, and for working out the monthly payment on the car itself the loan calculator covers the finance side. Every calculation happens in your browser, so the distances and prices you try stay on your device.

Frequently asked questions

How is fuel cost calculated?
It works out how much fuel the trip needs, then multiplies by the price. In miles-per-gallon mode the fuel needed is the distance divided by the mpg; in litres-per-100-km mode it is the distance times the economy divided by 100. Multiplying that volume by the price per unit gives the total, and dividing the total by the distance gives the cost per mile or kilometre.
What is the difference between mpg and L/100km?
Miles per gallon measures distance per unit of fuel, so a higher number is more efficient. Litres per 100 km measures fuel per fixed distance, so a lower number is more efficient. The calculator shows your figure converted to the other unit so you can read either one at a glance.
Does it handle round trips?
Yes. Switch the trip toggle to round trip and it doubles the distance you entered before working out the fuel and cost, which is the there and back total for a single journey. Leave it on one way for a single leg.
Which gallon does it use, US or UK?
In miles-per-gallon mode you choose. A US gallon is about 3.79 litres and a UK gallon about 4.55 litres, so the same mpg number means different real-world economy depending on which you mean. Pick the one your figure is quoted in for an accurate result.
Is my data uploaded anywhere?
No. Everything runs in your browser; nothing is sent to a server. The distances, prices, and economy figures you type are never uploaded, stored, or logged.

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